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  1. #1
    Join Date
    Feb 2008
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    2

    Question Furnace Ductwork placement

    I added a new room onto the back of my house on top of a concrete patio. The only way I have heat to this new room is from the adjoining kitchen vent and a vent I bored through a solid oak plate above the basement wall. The problem is I have the vent on the interior wall instead of the exterior mainly because I did not build up the floor of the new room other than OSB board and laminate flooring. The furnace is located in the basement and is a mere three feet from the wall where I extended the ductwork. The air now comes out really fast and not as warm as the rest of the vents. Is there proper placement of new ductwork in furnaces?, can I fix my problem without building up the floor and insulating under? Thank you

  2. #2

    Default Re: Furnace Ductwork placement

    I don't like the sound of making a big hole in the plate Hope you reinforced around the cut.There can be a damper installed to adjust air flow but if you don't have insulation its hard to keep warm.also is the room air being returned to the furnace some how-Under cut door or is the room open enough to the rest of the house. another point lets say the room is 200 square feet you need 200 cfm of heat or so if its insulated one vent is only about 100 cfm -since its uninsulated you need more- How much well concrete is a heat magnet . You could add a small ductless mini split for the room they work great.
    Hope this helps a little

  3. #3
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: Furnace Ductwork placement

    The furnace is located in the basement and is a mere three feet from the wall where I extended the ductwork.
    Andy .... curious ... how did you run the duct for the addition and what size?
    Had you tied the new duct to the furnace hot air plenum or the hot air supply trunk for this?
    Or did you simply "T" off the the existing duct from the kitchen?

  4. #4
    Join Date
    Feb 2008
    Posts
    69

    Wink Re: Furnace Ductwork placement

    Quote Originally Posted by Andy Nugent View Post
    I added a new room onto the back of my house on top of a concrete patio. The only way I have heat to this new room is from the adjoining kitchen vent and a vent I bored through a solid oak plate above the basement wall. The problem is I have the vent on the interior wall instead of the exterior mainly because I did not build up the floor of the new room other than OSB board and laminate flooring. The furnace is located in the basement and is a mere three feet from the wall where I extended the ductwork. The air now comes out really fast and not as warm as the rest of the vents. Is there proper placement of new ductwork in furnaces?, can I fix my problem without building up the floor and insulating under? Thank you
    Andy,

    Try putting an adjustable damper on that short line, to slow the air flow. They are simple to install. They are very similar to the old style dampers on the old time heater stoves. You might even try putting adjustable dampers on all the runs on this line, adjusting them until all show the same amount of heat. Some of the lines will probaby have to be open further than others.

    Good luck,

  5. #5
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: Furnace Ductwork placement

    You might even try putting adjustable dampers on all the runs on this line, adjusting them until all show the same amount of heat.
    I don't agree ..... This is a tricky thing to make additions to the furnace duct work.
    Simply adding dampers or extra ducts on a run can upset the balance of air flow in the entire system. This is something that should only be done with keeping proper CFM's in mind.

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